RefCountedThreadSafe   19 base/cancelable_callback_unittest.cc   friend class RefCountedThreadSafe<TestRefCounted>;
RefCountedThreadSafe   70 base/message_loop/message_loop_proxy_unittest.cc     friend class RefCountedThreadSafe<LoopRecorder>;
RefCountedThreadSafe   46 base/synchronization/waitable_event_watcher_posix.cc   friend class RefCountedThreadSafe<Flag>;